Here’s my thoughts on why the scrap suit is “eh” but not “awful.” Let’s crunch some numbers!
It has a coverage of 80%, which is around average; for armor you’re looking for the highest value you can get, because IIRC it directly reflects chance to tank a hit to the part. With 18 encumbrance to the torso, arms, and legs, it provides 10 bash and cut protection. That’s okay, but it’s far from great. Zombies mostly deal cut damage, so it’s nice, but the high encumbrance inhibits dodging substantially, and the lowish coverage means that the armor you’re mostly relying on isn’t very good at its job.
If you have goodish fabrication and need armor desperately, it’s an okay option. With tailoring you have direct upgrades for less material. Once you hit tailoring 5, you can make chitin arm guards, which are fantastic - 90% coverage and 10 encumbrance for 9/12 protection. For your torso, a Kevlar vest is nice - 5 encumbrance is nothing to scoff at for 85% coverage and 16 cut armor.
Overall, I’d rate it like I rate most improvised weapons such as the cudgel: It’s okay if you have nothing else, but once you have better, swap it out.